Setting tools are enormously useful for speeding any job requiring the setting of a large number of fasteners. Commonly, such tools are used in connection with setting fasteners in concrete or other hard materials. Because of the materials into which the fasteners are normally set, a substantial amount of motive force is required to be generated to set the fastener. This force is usually generated by the combustion of an energetic or accelerant material. While these tools are undeniably beneficial, they do require care in use to prevent unintended discharge of the fastener at a time when its discharge is unintended. Arrangements that assist in avoiding unintended discharge are always well received by the art.